Puerto Rico has been devastated by the most recent Hurricane and the country has reverted to cash only transactions in many places. This is something to keep in mind as you think about how to prepare, if you think about these things at all, for an event that could leave one on a cash transactional basis.
If you run out of cash then what? Barter? What would you have to barter? Some of the more common ideas are: alcohol, medicines, water, food, gold, silver, coffee, gas, oil, specialized services etc. Many of these are commodities at the present time and could become valuable barter items in the future.